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Full text of "Sorghum and sudangrass on the Prairies."

■ ^ Agriculture 



Canada 

Research Direction generate 
Branch de la recherche 



Technical Bulletin 1987-2E 




Sorghum and Sudangrass 
on the Prairies 



AGRICULTURE CANADA 
CODE 87/01/26 NO. 



LIBRARY/BIBLIOTHEQUE OTTAWA K1A OC5 



630. 
C759 
C 87 
00 A g 
c.3 




^wriS 




Canada 



The map on the cover has dots representing 
Agriculture Canada research establishments. 



Sorghum and Sudangrass 
on the Prairies 



DJ. MAJOR 

Crop Physiologist 

Agriculture Canada Research Station 

Lethbridge, Alberta 

H.H. JANZEN 

Soil Scientist 

Agriculture Canada Research Station 

Lethbridge, Alberta 

D.A. GAUDET 

Plant Pathologist 

Agriculture Canada Research Station 

Lethbridge, Alberta 

Lethbridge Research Station Contribution No. 10 



Research Branch 
Agriculture Canada 

1987 



Copies of this publication are available from: 

Dr. D.J. Major 

Plant Science Section 

Research Station 

Research Branch, Agriculture Canada 

Lethbridge, Alberta 

TIJ 4BI 



Produced by Research Program Service 

©Minister of Supply and Services Canada 1987 
Cat. No. A54-8/1 987-2 F. 
ISBN 0-662-15134-8 



CONTENTS 

SUMMARY/RESUME i 

INTRODUCTION 1 

SORGHUM TYPES 2 

GROWTH HABITS AND ADAPTATION 2 

USES 3 

Grain 3 

Forage 3 

PRODUCTION PRACTICES 8 

Seeding 8 

Fertility 12 

Weed Control 15 

Diseases 16 

Crop Rotation 18 

Harvest 23 

LITERATURE CITED 24 



- i 



SUMMARY 



Grain sorghum ( Sorghum bicolor L.) was evaluated as a new crop on the 
southern Prairies because of its reputation as a drought-tolerant crop. 
Dates of seeding, row spacing, stand density, fertility, dates and 
herbicide efficacy, diseases, methods of harvesting, and other agronomic 
studies were conducted. Under dryland conditions, sorghum had no better 
drought resistance than wheat and yields were not high enough to compete 
with conventional cereals. A need for breeding early, higher-yielding 
hybrids with resistance to seedling blight is indicated, and would 
require a heavy resource commitment to a high risk research venture. 
Sorghum- sudangrass (S_^ Sudanese [Piper Stapf.]) hybrids appear to have a 
place as a dryland and irrigated forage crop on the southern Prairies. 



RESUME 

Le sorgho grain ( Sorghum bicolor L.) a ete evalue comme culture 
eventuelle dans le sud des Prairies en raison de sa reputation de 
tolerance a la secheresse. On a conduit des essais sur les dates 
de semis, 1 ■ ecartement des lignes, la densite de peuplement, la 
fertilisation, les traitements herbicides, les maladies, les 
methodes de recolte, ainsi que sur d'autres carac teres agronomiques . 
En culture seche, le sorgho n'a pas demontre une meilleure resistance 
a la secheresse que le ble et ses rendements n'ont pas ete assez 
hauts pour lui permettre de faire concurrence aux cereales classiques. 
On se trouve devant la necessite de selectionner des hybrides precoces, 
plus productifs et possedant de la resistance a la brulure (fonte) des 
semis et, par ailleurs, les ressources a engager dans les recherches 
seraient considerables en regard des chances de succes. Les hybrides 
sorgho-soudan (_S. sudanense (Piper Stapf.)), en revanche, semblent 
offrir des possibilites pour cette region, tant en culture seche qu'en 
regime i rr i gue . 



- 1 



INTRODUCTION 

Grain sorghum ( Sorghum bicolor L.) is a potential alternative to 
traditionally grown cereal and forage crops in southern Alberta because 
of its C4-dicarboxylic acid photosynthetic pathway, which is believed to 
enhance adaptation to environments where water limits growth. Where 
sorghum is commonly grown, practical experience indicates that sorghum 
exhibits more drought resistance than most other crops (18). 

This report represents the culmination of 15 years of research at 
Lethbridge to assess the potential of sorghum in southern Alberta. It 
began with the selection of early sorghums from CIMMYT and, ultimately, 
early hybrids such as Pride P130 and Northrup King X8102. Studies were 
conducted on row spacings and densities (6), growth analysis (11), 
comparisons with other crops (7, 11), photoperiod responses (10), feeding 
value (1, 2), the effect of chilling temperatures on sorghum growth (12) 
and, most recently, the role of pathogens in stand establishment of 
sorghum (4, 5). 

Throughout these studies and in on- farm experiments in southern Alberta, 
stand establishment has been a problem. This has also been alluded to in 
many other studies. Ross and Webster (18) stated that the top 5-cm soil 
temperature should be about 20°C before seeding. Gaudet and Major (5) 
found that pathogenicity of seed-borne Pseudomonas and seed- and 
soil-borne fungi is increased by exposure to low temperatures. 
Consequently, the future of sorghum in the short-season regions 
ultimately depends on the selection of sorghums resistant to seedling 
blight ( Pseudomonas syrlngae ) . A concentrated breeding effort is 
required to accomplish this. 

The results of the current study indicate that, even when successfully 
established, sorghum yields may not be high enough to compete economically 
with wheat. The hope that sorghum would have higher drought resistance 
than wheat has not been realized. Rather, the ability of sorghum to 
thrive in arid conditions would appear to be related more to heat 
tolerance than to drought resistance (16). A breeding program might also 
be aimed at achieving a higher water- use efficiency. 



SORGHUM TYPES 

Sorghum and sudangrass ( Sorghum sudanense [Piper Stapf]), close relatives 
of corn and sugar cane, evolved in Ethiopia and the Sudan. They are 
widely grown in the southern U.S. (Nebraska south to Texas), northeast 
Africa, and India. Grain sorghums usually have dwarf genes associated 
with them so they only grow about 1 meter tall, whereas forage sorghums 
have no dwarf genes and grow to a height of about 2 meters. Three types 
are used for forage: forage sorghum, sudangrass, and sorghum-sudangrass 
hybrids. Forage sorghum has the highest dry matter yield under irrigation, 
but sudangrass, and sorghum-sudangrass hybrids are better on dryland. 

Initial research at Lethbridge was concentrated on dryland grain sorghum. 
This was aimed at developing early maturing sorghum cultivars and hybrids, 
a goal which was accomplished in less than 10 years. 



GROWTH HABITS AND ADAPTATION 

A major problem with sorghum production in southern Alberta is the poor 
stand establishment that results from reduced germination, emergence, and 
seedling growth at chilling temperatures. Sorghum requires a minimum 
soil temperature of 8-10°C for germination, while the optimum temperature 
is 24-28°C. The minimum temperature for seedling emergence is 10-12°C 
but a dramatic increase in percentage emergence occurs at temperatures 
above 20 °C. 

In southern Alberta, soil temperatures after early seeding are generally 
less than 15°C and, hence, limit germination and emergence. Consequently, 
early seeding to make use of the whole growing season may not necessarily 
be a good practice. Due to low soil temperatures, germination and 
seedling emergence are delayed, thus increasing the risk of seed decay 
and leaving the emerging seedling vulnerable to soil-borne disease. 
Further, prolonged exposure to chilling temperatures can kill sorghum 
seedlings. However, at locations in high latitudes such as Lethbridge, 
delaying seeding to allow the soil to warm increases the risk of frost 
before maturity. 

In order to assess the effects of short-duration chilling temperatures, 
an early maturing sorghum (Pride P130) was grown in a greenhouse with 
day/night temperatures of 23/18°C and transferred to a controlled 
environment chamber with day/night temperatures of 13/8°C for 3-, 7-, or 
10 -day periods starting at seedling emergence and continuing to maturity 
(12). Reductions in leaf number and plant height caused by chilling 
temperatures were only temporary. Chilling temperature 28 days after 
emergence caused tiller numbers to increase from three to as many as 
eight per plant. 



- 3 



Most of the tillers appeared in a 14-day period starting about 10 days 
after emergence (Fig. 1). Exposure to chilling temperature during the 
short period when the plants were reaching maximum tiller number promoted 
tillering. The maximum enhancement of tillering occurred at about day 
28, when all of the tillers were visible in the control treatment. 
Exposure to chilling temperatures caused the production of about two, 
five, or four additional tillers for the 3-, 7-, and 10-day exposures. 
This is consistent with previous reports that tillering response of 
sorghum to chilling treatment is dependent on the plant's age. 

To determine if above- freezing temperatures affected emergence, P130 
sorghum and Pride 1108 corn were planted in sand and left for 3 days in 
the greenhouse. The flats were exposed to 0.5°C, 5°C, or 10°C for 
various lengths of time and then returned to the greenhouse. The 
percentage of seedlings killed at the three temperatures indicated that 
Pride 130 sorghum was much more sensitive to cold temperature exposure 
than Pride 1108 corn. Figure 2 demonstrates how the percentage of seeds 
that germinate increases from zero at about 4°C to 98% at 14°C and how 
the time to germinate decreases from 7 days to less than 1 day. Other 
experiments clarified the role of low temperatures on emergence. Low 
temperatures per se are not a problem but they do reduce the vigour of 
the sorghum seedling and its ability to resist soil- and seed-borne 
pathogens. Thus, there was no physiological damage or chilling injury 
due to low temperatures so reduced emergence was the result of a number 
of factors such as inability to overcome soil impedence and to withstand 
soil-borne pathogens and the infection of Pseudomonas syringae . 



USES 

Grain 

Grain sorghum is not currently recommended for Alberta but there have 
been situations in which it has been produced. Sorghum is a coarse grain 
with nutritional characteristics very similar to those of corn. However, 
it generally does not command as high a price as does corn. The 
consumption of grain corn is primarily in two distilleries (52 000 
tonnes) and in feed manufacturing (18 000 tonnes). The sorghum used in 
feed would likely be mainly in poultry feed. The grain used for 
distilling is used for producing whiskey, gin, and vodka and for other 
commercial alcohol uses. 



Forage 

Forage sorghum trials have been conducted at Lethbridge, Brandon, Morden, 
and Ottawa since 1980. A summary of these trials indicated that forage 
sorghums will provide a competitive alternative to the cereals for dryland 
forage production on the southern Prairies (Table 1). 



4 - 




4 r 



LU 

CD 3 



2 - 



cr 

UJ 

_J 



Tiller No. 



3.005 



, . _< 15 193-0.853 doys) 
I + e 



10 20 30 40 50 

DAYS FROM EMERGENCE 



60 



Fig. 1. Non-linear regression analysis of tiller number (excluding the 
primary tiller) vs. days from seedling emergence and changes in tiller 
number caused by the chilling temperature vs. days Erom seedling emergence 
for Pride PI 30 soybeans. 



- 5 



• Pride PI30 - SORGHUM 

o Pride 1108 - CORN 



0°C (SORGHUM ) 



Q 
l±J 



< 



UJ 
O 

cr 

L±J 
0_ 



100 -i 



80- 



60- 



40- 



20- 




EXP0SURE (days) 



Fig. 2. The effect of length of exposure to various temperatures after 
germination but prior to emergence on percentage of seedlings of Pride 
P130 sorghum killed at 0, 5, and 10°C and of Pride 1108 corn killed at 
and 5°c. 



Table 1. Average performance of selected forage sorghums (FS), 

sorghum- sudangrass (SS) hybrids and sudangrass (SG) at Morden, 
Brandon, Ottawa, and Lethbridge from 1978- 1984. 



Year/Hybrid 


Type 


Lethbridge 


Brandon 


Morden 


Ottawa 








- tonnes/ha 












1980 












Pioneer 988 


SS 


4.39 






16.4 


Pride PF70 


FS 


5.22 






15.3 


Pioneer 931 


FS 


5.12 






16.6 


Pioneer 988 


SS 


4.39 






16.4 


Trudan 


SG 


4.33 






11.7 


1981 












Pride PF70 


FS 


6.69 


11.98 


14.08 


19.85 


Pioneer 931 


FS 


7.01 


7.87 


12.10 


17.41 


Pioneer 988 


SS 


5.77 


8.93 


9.33 


12.64 


Sordan 


SG 


6.12 


10.48 


10.02 


12.38 


1982 












Pride PF70 


FS 


7.85 


7.18 




16.59 


Pioneer 931 


FS 


8.40 


9.13 




16.89 


Pioneer 988 


SS 


8.24 


8.60 




13.52 


Sordan 


SG 


8.68 


7.24 




10.43 


1983 












Pride PF70 


FS 


9.61 


12.79 


7.62 


13.55 


Pioneer 931 


FS 


9.80 




6.21 


14.86 


Pioneer 988 


SS 


8.29 


14.77 


4.54 


12.03 


Sordan 


SG 


7.59 


16.61 


4.88 


11.81 


1984 












Pride PF70 


FS 


4.57 


7.20 


16.34 


18.14 


Pioneer 931 


FS 


4.61 


12.60 


21.12 


16.82 


Pioneer 988 


SS 


3.92 


9.60 


15.62 


14.28 


Sordan 


SG 


3.43 


12.16 


16.00 


11.20 



7 - 



The combination of fall rye followed by sorghura-sudangrass is ideal for 
double cropping where irrigation is available. The fall rye heads out in 
late May and is ready to harvest for silage by the third week of June. This 
is followed immediately by seeding sorghum- sudangrass, which is harvested in 
late August or early September. Yields of double cropping have been similar 
to yields of maize grown at Lethbridge (Table 2). There are still some 
difficulties such as slow growth of sorghum immediately following the rye 
harvest. Additional research is required to determine the cause of this. 



Table 2. Component yield of various crops grown in double cropping 
and of maize grown under irrigation at Lethbridge in 1984-86. 



Year 



Crop 



Winter cereal 



Sorghum- sudangrass 



Maize 



1983-84 
1984-85 
1985-86 



7.0 
4.3 
8.7 



tonnes/ha 
8.1 
6.7 
7.9 



12.7 
13.5 
17.9 



Prussic acid poisoning mainly occurs when livestock are fed green-chop 
sorghum-sudangrass or are pastured on young sorghum or regrowth. It is 
caused by dhurrin, a cyanogenic glucoside, which hydrolyzes to form the 
respiratory poison, hydrogen cyanide, when ingested by animals. A 450-kg 
cow will be killed by 1 gram of hydrogen cyanide, which could be present 
in less than 2 kg of plant material. Most sudangrasses have been bred 
for reduced levels of dhurrin but there are circumstances in which lethal 
levels may still occur. Young regrowth, particularly after a killing 
frost, is most dangerous. Nitrogen fertilization increases the levels of 
dhurrin and levels can also increase when growth is slowed by injury, 
moisture stress or cold temperatures. A New Zealand study (8) indicated 
that irrigated crops contained 30-40% less prussic acid than those on 
dryland. This difference would be magnified in southern Alberta because 
of our extreme drought on dryland. In a crop containing lethal levels of 
HCN, cattle will succumb within half an hour. Therefore, in potentially 
dangerous situations, the feed should be analyzed before free access to 
the crop is given. Where sorghum green- feed constitutes a major part of 
the animals' diet, dietary supplementation with sulfur (1.2 g sulfur/g 
HCN) will detoxify the feed (8). Cutting the crop for hay or silage will 
result in disappearance of most or all of the dhurrin. 



- - 

PRODUCTION PRACTICES 

Seeding 

Sorghum- sudangrass hybrids will produce more dry matter than annual 
cereals such as barley or oats. The crop should be seeded between 25 May 
and 15 June. Seeding too early into cold soils can result in poor 
emergence due to cool soil. Later seeding may not allow enough time for 
the crop to make maximum growth before frost. The crop should be ready 
for harvest in late August. 

Seeds of sorghums of all types are susceptible to damage in adverse soil 
conditions, particularly when the soil is cool. Therefore, seeding should 
not begin until the day-time temperature of soil at 5- cm depth is about 
20°C. As a rule of thumb, this will be after 25 May. In a date-of-planting 
study conducted at Lethbridge, the percentage seeds established increased 
as planting date was delayed after 15 May. However, yield decreased due to 
later maturity of late-seeded sorghum. In practice, the most appropriate 
course of action is to delay seeding. Therefore, a hybrid chosen for 
seeding in late May must be capable of reaching maturity before fall frost. 

To assess the effect of stand on yield, a seeding rate experiment was 
conducted with P130 in 1980 and P145 in 1981 and 1982. Seeding rates 
ranged from 5 to 90 kg/ha and the variables measured were stand 
establishment (plants/m^) and yield. Population densities increased with 
seeding rate but the percentage emergence was generally constant (Table 3). 
The positive relationship between seeding rate and population density 
decreased in 1982 compared with 1980 and 1981. This reduction may have 
been due to increased interplant competition at the high seeding rates in 
1982. There were essentially no differences in yield in spite of an 
18-fold difference in population density. In 1981 and 1982, there were 
slight reductions in yield at the 5, 10, and 90 kg/ha rates but not at 
the 15 to 60 kg/ha rates. These results indicated that a seeding rate of 
about 15 or 20 kg/ha should be suitable in short- season areas. 

The relationship between the number of heat units and relative yield was 
determined from data on the effect of seeding and harvest dates collected 
at Lethbridge from 1978 to 1982 (13). For the hybrid in question, Pride 
P145, 2400 corn heat units (CHU) were required to get maximum yield 
(Fig. 3). Coincident with a reduction in yield was a reduction in test 
weight. If the crop did not receive sufficient CHU to mature then the 
seed was light and shrunken. Only the regions around Bow Island and 
Medicine Hat would have sufficient CHU to allow seeding in late May and 
still reach maturity. For dryland situations, sorghum- sudangrass hybrids 
seeded in late May will have extracted most of the available soil 
moisture by the end of August, in most years. Thus, the main criterion 
for sorghum-sudangrass is not when grain maturity can be reached but how 
long it takes the crop to extract all of the available moisture. 



9 - 



Table 3. The effect of seeding rate on final population density and 
grain yield of P130 (1980) and P145 (1981 and 1982) sorghum grown 
at Lethbridge, Alberta. 



Seeding 


rate 


Population density 
(plants/m 2 ) 


Yield (kg/ha) 






(Kernels/ 
m 2 ) 




(kg/ha) 


1980 


1981 


1982 


1980 


1981 


1982 


5 




24 


10.2 


14.1 


12.0 


1409 


4400 


844 


10 




47 


16.4 


25.9 


19.6 


1709 


4754 


1080 


15 




71 


29.7 


35.2 


21.6 


1765 


5407 


1419 


20 




95 


31.1 


43.9 


34.0 


1561 


5517 


1550 


25 




118 


42.6 


55.7 


41.0 


1590 


5579 


1634 


30 




142 


52.8 


62.1 


43.4 


1572 


5763 


1332 


40 




189 


58.6 


85.3 


52.6 


1566 


5484 


1610 


50 




236 


91.0 


96.9 


61.8 


1731 


5353 


1284 


60 




284 


106.3 


90.2 


63.8 


1843 


4973 


1387 


90 




426 


132.1 


152.3 


87.6 


1664 


4775 


1100 


Mean 






57.1 


66.2 


43.8 


1641 


5201 


1324 


LSD 05 






19.1 


25.3 


4.9 


386 


591 


298 



The critical factor in depth of seeding is to place the seed into 
sufficient moisture for it to emerge before the soil dries out. If 
seeded 2-3 cm deep in late May, sorghum will emerge in about 7 days. In 
a depth-of-seeding experiment in 1982 we found that the optimum seeding 
depth was about 4 cm. At shallower seeding depths, stand establishment 
was reduced because of soil drying; at deeper seeding depths, poor 
emergence and stresses introduced by late emergence reduced yield. If 
the soil is too dry, deeper seeding will be necessary. 



Disc drills are preferable to hoe drills in a double cropping system 
because they appear to place the seed more gently into the soil than hoe 
drills. Discers are generally not recommended for sorghum, but if they 
must be used the seeding rate should be increased. To date, the biggest 
problem has been providing a good seed bed immediately after the harvest 
of the first crop. An irrigation followed by zero-till seeding into the 
stubble will give the best results. Forage sorghum should be seeded at 
15 kg/ha (about 15 lb/acre), sorghum sudangrass hybrids at 20 kg/ha and 



- 10 - 



RELATIVE YIELD = 0.936 



/[■* 



( 11.4 - 0.00569C 



HU) "I 



I.O-i 



Q 0.8" 



UJ 

>- 



Ixl 

> 



LU 



0.6- 



4- 



0.2- 




"i r 

1400 1600 1800 2000 2200 2400 

CORN HEAT UNITS (CHU) 



2600 



Fig. 3. The relationship between relative yield of sorghum and the 
number of corn heat units accumulated between planting and harvest for 
four planting and four harvest dates at Lethbridge in 1978-1982. 



Table 4. Effect of row spacing on grain yield and grain yield components 
of Pride X4004 and Pride X4053 sorghums in experiment 1 and 2, 1973 
and in experiment 3, 1974. 







Row 


Grain 


Yield per 


Panicles 


per 






spacing 


yield 


panicle 












Experiment 


Hybrid 


(cm) 


(kg/ha) 


(g) 


Plant 


m^ 


1 


Pride X4004 


36 


2,904a 


4.78c 


3.52 


61.2a 






72 


2,444b 


4.83c 


2.87b 


52.4b 




Pride X4053 


36 


2,150b 


7.62b 


1.59c 


28.4c 






72 


2,372b 


9.07a 


1.54c 


27.1c 


2 


Pride X4004 


36 


1,799a 


2.94c 


4.43a 


62.6a 






72 


l,544ab 


2.72c 


4.24a 


57.9a 




Pride X4053 


36 


1,321b 


4.72b 


2.15b 


27.9b 






72 


1,396b 


5.66a 


1.82b 


24.6b 


3 


Pride X4004 


18 


3,808a 


6.57a 


4.24a 


57.6a 






36 


3,427a 


6.63a 


3.87a 


51.6a 






72 


3,458a 


6.73a 


3.88a 


50.9a 



a-c Within columns, within experiments, means followed by the same letter 
do not differ at the P = 0.05 probability level using Duncan's multiple 
range test. 



- 11 



sudangrass at 25 kg/ha using a row spacing of approximately 40 cm. For 
most drills, it is desirable to plug or tape over the openings above every 
other run to provide wider row spacings. If corn equipment is available, 
seeding can be done in 75- cm (30") rows with no loss of yield. 

Sorghum yields are not generally affected by row spacing. Three 
experiments were conducted at Lethbridge in 1973 and 1974 to determine 
the effect of row spacing and plant densities on sorghum yield (6). 

The only effect of row spacing on grain yield was in experiment 1, which 
resulted in higher grain yield for X4004 (Table 4). The yield component 
results, however, indicated a differential response of the two hybrids 
X4004 and X4053 to row spacing. As row spacing increased, panicles per 
plant and panicles per square meter decreased for X4004 but yield per 
panicle remained unchanged. The hybrid X4053, in contrast, had increased 
yield per panicle as row spacing increased but panicles per plant and 
panicles per square meter remained unchanged. 

Increased population density had no consistent effect on grain yield in 
experiments 1 and 3, but in experiment 2 yield increased as population 
density increased (Table 5). Experiment 2 was on the driest of the three 
sites. The plants established slowly and were always smaller than the 
plants in the other experiments at comparable times during the season. 
In all experiments, as population density increased, panicles per plant 
decreased but panicles per square meter increased. Yield per panicle 
decreased with increasing population density in experiments 1 and 3, but 
there was no significant response in experiment 2. 

Significant hybrid X population density interactions were detected for 
panicles per plant and panicles per square meter in experiment 2. The 
hybrid X4004 appeared to have a greater capacity to produce seed- bearing 
tillers at low population densities. No significant interactions of row 
spacing X population density were detected for yield or its components. 

It was evident that tillering capacities of X4004 and X4053 were important 
in stabilizing grain yields over a wide range of population densities. 

On dryland, 75-cm wide rows will allow for some early season competition 
within the row and conserve the moisture between the rows for late season 
growth. These wide rows will also allow cultivation of the crop, which 
has some value in weed control, allowing more uniform infiltration of 
moisture and aeration of the soil. The disadvantage of wide rows comes 
at harvest time since the stubble will not support a swath and a corn 
head may be required for the forage harvester. 

The seasonal pattern of sorghum whole plant dry weight accumulation, 
studied at Lethbridge in 1976 and 1977, was similar for wheat and barley 
but growth started later and continued later in the season (Fig. 4). In 
1976, whole plant growth of barley and wheat levelled off about 1 Aug. 
and, in 1977, about 15 July for barley and 15 Aug. for wheat (11). 



12 



Whole-plant growth of sorghum continued well into September in both years 
but the increase was small after 15 Aug. in 1977. Sorghum grain yield 
increased until 15 Sept. During the period 15 Aug. -15 Sept. of both 
years, sorghum leaf, stem, and head dry weight decreased. Growth of 
leaves and stems of barley maximized about 1 July in 1976 and 1977, and 
only seed yield and whole- plant yield continued to increase. Wheat leaf, 
stem, and head dry weights stayed the same or decreased after 15 Aug. and 
15 July in 1976 and 1977, respectively, while seed dry weight continued 
to increase. 

Whole-plant and grain growth rates were estimated during the linear phase 
of growth (Fig. 4). Sorghum had significantly higher whole-plant growth 
rate than wheat but not barley. Grain growth rate did not differ among 
the three species in 1976 but barley grain growth rate was highest in 
1977. In 1976, yields of barley and sorghum were similar because grain 
growth rates and filling periods were similar. Wheat grain growth rate 
and filling period tended to be lower than both barley and sorghum, 
although not always significantly different. Nevertheless, the grain 
yield of wheat was consistently lower. 

Although sorghum matured 40 days later than either wheat or barley, its 
effective whole-plant duration (58 days) was not significantly greater than 
that of barley (50 days). The effective filling period duration was the 
same (31 days) for the three species in 1976, but longer for sorghum (40 
days) than for barley in 1977 (26 days). Barley had a higher daily grain 
growth rate (150 kg/ha) than sorghum (109 kg/ha) in 1977, but, because of 
a shorter filling period, grain yield was not significantly lower. 



Fertility 

Sorghums are highly responsive to nitrogen if there is sufficient soil 
moisture for crop growth as demonstrated by Hobbs and Krogman (7) at 
Vauxhall. In a double- cropping situation, N should be applied in split 
applications or with the irrigation system to minimize leaching. On 
dryland, sorghum should be fertilized in the same manner as cereal 
crops. For every metric tonne of dry matter per hectare there will be 15 
kg of N and 6 kg of P2O5 removed from the crop. A 5.6 tonne/ha crop 
of sorghum hay at 15% moisture translates to 70 kg of N/ha and 30 kg of 
P20 5 /ha. For a double crop with a yield of 22 wet tons/ha of fall 
rye and 27 wet tonne/ha of sorghum, nutrient uptake from the soil will be 
200 kg N/ha and 80 kg P 2 5 /ha. 



- 13 - 



1976 



1977 



200r 



LEAVES 



E 



X 

o 

Ld 



>- 

or 

Q 




400 




200 



WHOLE PLANT 









- 




x -x-*-v x / 


/ 


X J 




- /// 


1 


1 111 



S.E. i i i I I I I III illli 



X. X 



XXIIII illlllll 



I I I I I I I I ' I I 1 L_ 

I 15 I 15 I 15 I 15 28 I 15 I 15 

JUNE JULY 



J I I 



AUG SEP 



JUNE JULY 



15 I 15 27 

AUG SEP 



Fig. 4. Seasonal changes in dry weight of plant components and standard 

errors of whole plant dry weights for sorghum (x x) , wheat (o o) , 

and barley (• •) in 1976 and 1977. 



14 - 



Table 5. Effect of population density on grain yield and grain yield 
components of Pride X4004 and Pride X4053 sorghum hybrids in 
experiment 1 and 2, 1973 and in experiment 3, 1974. 







Population 

density 
(plants/ha) 


Grain 

yield 

(kg/ha) 


Yield per 
panicle 

(g) 


Panicl 


es per 


Experl 


Ltnent Hybrid 


Plant 


m^ 


1 


Pride X4004 


87,000 


2,827a 


6.25bc 


5.19a 


44.9b 






173,000 


3,009a 


5.04cd 


3.45b 


59.7a 






260,000 


2,494a 


4.07d 


2.34d 


60.8a 






346,000 


2,366a 


3.86d 


1.79e 


61.9a 




Pride X4053 


87,000 


2,146a 


8.88a 


2.78c 


24. Od 






173,000 


2,299a 


9.67a 


1.41ef 


24. 4d 






260,000 


2,180a 


7.98ab 


1.06f 


27. 5d 






346,000 


2,419a 


6.86bc 


1.02f 


35.2c 


2 


Pride X4004 


80,000 


l,462abc 


3.15b 


5.87a 


46.5c 






150,000 


l,708ab 


2.91b 


3.94b 


58.4b 






240,000 


1,846a 


2.44b 


3.19c 


75.7a 




Pride X4053 


80,000 


1,120c 


4.82a 


2 . 98c 


23. 6d 






150,000 


l,343bc 


5.38a 


1.69d 


25. Id 






240,000 


l,612ab 


5.36a 


1.27d 


30. Id 


3 


Pride X4004 


75,000 


3,677a 


7.87a 


6.22a 


46.7b 






150,000 


3,670a 


6.11b 


3.96b 


59.3a 






300,000 


3,344a 


5.96b 


1.80c 


54. lab 



a-f Within columns, within experiments, means followed by the same 
letter do not differ at the P = 0.05 probability level using 
Duncan's mutiple range test. 



- 15 - 



Weed Control 

Weed control studies to determine if conventional sorghum weed control 
practices are effective in short-season areas have been conducted at the 
Lethbridge Research Station. Atrazine is the most effective herbicide 
but the persistent residue may be of concern. The most consistent weed 
control is achieved by a fall application of atrazine at a rate of 1 kg 
a.i./ha. Spring applications without incorporation with a double disc and 
harrow have not always been successful because of the low, unpredictable 
rainfall. Other effective herbicide treatments are bromoxynil plus MCPA 
or 2,4-D up to the 6- leaf stage. 

Two major weed problems are Russian thistle, which has some atrazine 
resistance, and green foxtail. Green foxtail can be controlled in 
rotation with cereals or by using a pre-plant incorporated treatment of 
atrazine + raetolachlor and a seed safener. 

Sorghum growing in short-season areas requires protection from weed 
infestations for the entire summer as it does not provide enough ground 
cover to provide competition against weeds even late in the year. The 
development of early sorghum hybrids should allow delayed seeding to be 
combined with a late cultivation to control late-emerging weeds. Weed 
control problems in Alberta are similar to those described by Ross and 
Webster (18) in Nebraska. 

Weeds can be a problem on double cropping but usually both the winter and 
summer crops, when adequately supplied with water and fertility, provide 
ample competition to eliminate all weed growth. In some situations, 
broadleaf weeds such as lamb's quarters and red-root pigweed are a 
problem in the summer crop. On dryland, Russian thistle, in particular, 
has been the primary problem. 

If a commitment is made to sorghum production then atrazine provides the 
best and cheapest form of weed control. This should be applied in the 
fall at the rate of about 2 kg/ha in the first year and then lesser 
amounts in subsequent years. One application of about 1 kg/ha of 
atrazine is sufficient to control most weeds. 

Atrazine appears to break down in southern Alberta soil at a rate of 
about 75%/year depending on rainfall. Breakdown will occur when the soil 
is moist but will be delayed in dry soil. An annual application of 
atrazine at 1 kg/ha will result in a buildup in the soil so it should 
only be applied the fall before seeding. An ideal rotation including 
sorghum is a winter wheat/sorghum/fallow rotation. Atrazine is applied 
after the winter wheat harvest at 1.5 kg/ha. This provides weed control 
through the sorghum year and into the summerfallow year. At the time of 
the sorghum harvest there will be about 0.4 kg/ha of atrazine and when 
the winter wheat is seeded the following year there will be about 0.1 
kg/ha of atrazine. 



16 - 



If atrazine is not used, then herbicides such as 2,4-D and Buctril M will 
provide control of many broad leaf weed problems. 



Diseases 

A study conducted to assess the factors influencing seedling emergence 
(5) showed that the type of soil and seed source affected seedling 
emergence. Autoclaving the soil to kill soil-borne organisms resulted 
in higher emergence at 15/5°C regime (Table 6) compared with unautoclaved 
soil. Cornell mix, which is a greenhouse mixture of equal parts of 
sand, peat, and vermiculite, was very porous and caused less impedance 
to the seedling than did soil. In this study, two soil-borne organisms, 
F usarium tricinctum and F_^ oxysporum , were used to inoculate soil 
planted to disease-free seed. It was clear from these results that the 
capacity of soil-borne fungi to infect sorghum seedlings was enhanced at 
low temperatures. This explains why only about 30% of the seed emerges 
when the crop is seeded in early May and about 90% emerges when it is 
seeded in early June. Another pathogen infects the flower at heading 
time and it may also be involved in reduced seed set, shrivelled seeds 
and low test weight. Infected seed will also exhibit reduced vigour and 
lead to poor emergence of the following crop. 



Table 6. The combined percent emergence of three sorghum 

cultivars grown in two autoclaved rooting media at 30/20°C 
and 15/5°C day/night temperatures when inoculated with 
Fusarium oxysporum and F. t ricinctum . 



Percentage emergence 



30/20°C 15/5°C 



Rooting medium 

Cornell mix 94a 70a 

Lethbridge loam soil 78b 40b 

Isolate 

Check 90a 82a 

F. oxysporum (No. 1) 93a 46bc 

F. oxysporum (No. 2) 79a 57b 

F. tricinctum 82a 35c 



a-c Means within columns and within treatments followed by 

the same letter did not differ at the P = 0.05 probability 
level using Duncan's Multiple Range Test. 



- 17 - 



Table 7. Percentage germination, root and shoot length, percentage 

discoloration, and incidence of P^ s^ syrlngae in surface-sterilized 



and unsterilized sor 


ghum seedlots. 












Treat- 
ment * 


Germi-^ 
nation 
(%) 


Root 

length 

(mm) 


Shoot 
length 
(mm) 


% of seedlings with 


Seedlot 


Discolor- 
ation 


P 
syi 


._ s. 
ringae 


CL-12 


US 


99 


24**§ 


12** 


10++H 




21++ 


CL-12 


ss 


100 


32 


18 


2 




9 


CL-16 


us 


83 


28** 


13** 


31++ 




67++ 


CL-16 


ss 


82 


45 


30 


13 




15 


X8101 


us 


92 


28** 


21** 


32 




47++ 


X8101 


ss 


96 


47 


29 


22 







P145 


us 


78 


32 


19 


35+ + 




51++ 


P145 


ss 


78 


34 


21 


11 




19 


LB 


us 


59+ + 


18 


14 


n.d. 




62++ 


LH 


ss 


78 


20 


16 


* * 
n.d. 




11 


F-l (1983) 


us 


75 


21 


9 


30+ 




8 


F-l (1983) 


ss 


77 


22 


8 


18 




6 


F-l (1984) 


ss 


18 


15 


6 


5 




61++ 


F-l (1984) 


us 


18 


18 


8 


16 




27 


F-2 


us 


46 


25 


14 


32 




26+ 


F-2 


ss 


29 


26 


15 


35 




10 


F-3 


us 


76 


23 


8 


26 




18 


F-3 


ss 


83 


26 


12 


13 




12 


100M 


us 


100 


42 


22 










100N 


ss 


98 


45 


20 











'SS = surface sterilized, US = unsterilized. 

+A seed was considered germinated if extension of the coleoptile and/or 

coleorhiza was observed. 
s Means within lots significantly different at *, P = 0.05 and **, P = 0.01 

using analysis of variance. 
Cleans within lots significantly different at +, P = 0.05 and +f, P = 0.01 

using chi- square test for homogeneity. 
*n.d. = no data 



- 18 - 



A seed-born bacterium, Pseudomonas syringae pv. syringae ( P. s. syringae ) , 
was identified as a cause of stunting and discoloration of the roots and 
coleoptiles of sorghum seedlings (4). The incidence of P^ s_^ syringae in 
nine lots of field-grown sorghum seed (Table 7), produced in 3 different 
years in southern Alberta, varied from 8 to 67% (average = 38%). Surface 
sterilization of seed with 10% sodium hypochlorite reduced stunting and 
necrosis of root and shoot tissues from hand-harvested, but not from 
mechanically harvested, seedlots. This indicated that the bacteria were 
internally borne within the seed of mechanically harvested seeds and on 
the surface of hand-harvested seedlots. Internal infection of the seed 
by P^ s^ syringae may be promoted by mechanical damage to the seed which 
occurs during harvesting. Sorghum seedlings from seed inoculated with 
strains of P^ s^ syringae developed stunted and discolored roots and 
coleoptiles when placed on moist filter paper and yielded fewer emerged 
seedlings than uninoculated controls when sown in autoclaved or untreated 
field soil in a growth chamber. Strains of the pathogen differed 
markedly in the severity of symptoms produced in sorghum seedlings. 

However, there is still a problem with disease. Due to its susceptibility 
to cold temperatures, sorghum can be infected by soil- and seed-borne 
pathogens that seriously reduce emergence. 



Crop Rotation 

Agriculture in the nonirrigated areas of southern Alberta is primarily 
limited to cereal production because of low precipitation (400 ram per 
year) and a short growing season length (117 frost-free days). This 
virtual monoculture production system results in excessive reliance on 
summer fallowing, overdependence on economic returns from single crops, 
and reduced opportunity for weed and pest control. Consequently, the 
introduction of new crops and diversification of cropping systems would 
potentially provide both economic and agronomic benefits to southern 
Alberta agriculture. 

Thus, while the potential to develop sorghum hybrids to reach maturity in 
southern Alberta has been demonstrated (10) and many of the production 
practices such as dates of seeding, rates of seeding, and row spacing have 
been defined (6, 13), the agronomic and economic feasibility of sorghum 
production as an integral part of dryland agriculture in the southern 
Canadian Prairies has not been adequately considered. Therefore an 
intensive long-term rotation experiment was conducted from 1978 to 1984, 
to determine the response of sorghum in rotation with other crops grown 
in southern Alberta (9). 

Sorghum yields ranged from 1161 to 2474 kg/ha in the various rotations 
averaged over the 5-year period (Table 8). Highest yields were observed 
when sorghum followed fallow in the rotation, regardless of rotation 
length. Significantly lower sorghum yields were observed in 3-year 
rotations where sorghum followed spring or winter wheat. Still lower 



- 19 - 



yields were observed when sorghum succeeded sorghum and lowest yields 
occurred when sorghum followed barley in the rotation. The high yields 
observed after fallow were probably almost entirely attributable to 
greater availability of moisture. The relatively good performance of 
sorghum after winter wheat may be partially the result of a disease 
outbreak in the winter wheat during 1981 which required plowing down of 
the winter wheat in midseason and resulted in a partial fallow period 
prior to sorghum establishment. The relatively low yields observed in 
the continuous sorghum and sorghum-barley rotations were attributed to 
increased infestation of weeds such as Russian thistle and kochia. On 
average, the ratio of yield on stubble to yield on fallow was 0.63 for 
sorghum and 0.69 for spring wheat. The number of crops preceding the 
fallow year had no effect on sorghum yield after fallow as is evident in 
the comparable sorghum yield for rotations S-SW-F and S-F (Table 9). 



Table 8. Effect of the preceding crop on the yield of 
sorghum in a study comparing six sorghum rotations 
grown at the Lethbridge Research Station (1978-1984). 



Sorghum yield* 
Rotationt Preceding crop (kg/ha) 



S-SW-F Fallow 2474a 

S-F Fallow 2415a 

S-F-WW Winter wheat 1849b 

S-F-SW Spring wheat 1712b 

S Sorghum 1466c 

S-B Barley 1161d 

•S = sorghum, SW = spring wheat, F = fallow, WW = winter 
wheat, B = barley. 

+Yield values followed by the same letter are not 
significantly different at P = 0.05 based on calculated LSD. 



Highest overall rotation yields were obtained for the continuous cropping 
rotations, the sorghum- bar ley rotation, and the continuous sorghum 
rotations. The lowest total yield was obtained for the sorghum- fallow 
rotation (Table 9). The 30-year mean total precipitation at Lethbridge 
was 405 mm and all but one of the years of this study had crop year 
precipitation that was at least 75% of average. Thus, it is probable 
that over a 100-year period there would be years with considerably less 
precipitation than was encountered in this study. Also, the region of 
southern Alberta which would be most likely to produce sorghum receives 
even less precipitation than does Lethbridge. Therefore, it would not be 
prudent to recommend continuous cropping throughout southern Alberta 
based on the results of our research. 



- 20 - 



Table 9. Yields in a study comparing six sorghum 

rotations grown at the Lethbridge Research Station 
(1978-1984). 





Crop 


Yield 


( kg/ha )+ 


Rotation 


Per crop 


Per rotation 


S 


Sorghum 


1466 


1466b 


S-F 


Sorghum 


2415 


1207d 




Fallow 







S-B 


Sorghum 


1161 


1670a 




Barley 


2180 




S-SW-F 


Sorghum 


2474 


1374bc 




Spring wheat 


1649 






Fallow 







S-F-SW 


Sorghum 


1712 


1334cd 




Fallow 









Spring wheat 


2450 




S-F-WW 


Sorghum 


1849 


1433bc 




Fallow 









Winter wheat 


2450 





'Yield values followed by the same letter are not 
significantly different at P = 0.05 based on calculated 
LSD. 



Mean rotation yields ranged from 577 kg/ha in 1984 to 1968 kg/ha in 1980, 
probably reflecting differences in levels of available soil moisture. The 
differences attributable to variability in precipitation were greater than 
any differences detected among the rotations. This emphasizes the critical 
role played by rainfall in the dryland agriculture of southern Alberta. 

The major limitation to crop production in southern Alberta is the 
availability of moisture. Between 44 and 79% of the variability in yields 
of sorghum and wheat in this study was accounted for by differences in 
growing season precipitation and the relationship was strongest in stubble 
crops, where moisture deficits were most severe. The effect of moisture 
on yield was best demonstrated in the relationship between yield and total 
available moisture levels (Fig. 5), defined as available spring soil 
moisture plus growing season precipitation. For wheat fallow, total 



- 21 - 



available moisture accounted for 97% of the variability in yield. The 
regression coefficients for the relationship between yield and total 
available moisture were similar for sorghum (1.30 kg/m 3 ) and for wheat 
(1.35 kg/m 3 ) when seeded on fallow. The regression coefficients were 
also similar to each other but lower when seeded on stubble: 1.11 and 
1.12 kg/m 3 , for sorghum and wheat, respectively. The X-intercept of 
the relationship represented the minimum available moisture required to 
produce sorghum yields. The values obtained were 95 and 102 ra 3 /ha for 
sorghum on stubble and fallow, respectively. The corresponding values 
for spring wheat were 85 and 124 m 3 /ha, respectively. Based on these 
estimates, there was no evidence that sorghum possessed an advantage in 
drought resistance or water-use efficiency over wheat under southern 
Alberta conditions. While our estimates of total available moisture may 
not have been an accurate estimate of total evapotranspiration, our 
water-use efficiencies were reasonably close to those published by Porter 
et al. (17), Olson (15), Garrity et al. (3) and Stewart et al. (19). Our 
values were within the range of values that Garrity et al. (3) obtained 
for a crop that used about 300 mm of water. They found that water-use 
efficiency increased as total evapotranspiration increased. This would 
be the case when comparing our fallow with stubble conditions. The 
values that Neild (14) obtained were somewhat higher than our 2 kg/m 3 
but he obtained his estimate for sorghum grown in a higher rainfall 
region than occurs in southern Alberta. The relationship that Stewart et 
al. (19) obtained was very much like the one obtained in this study. 
Theirs had an X-intercept of 143 m 3 /ha as minimum evapotranspiration 
for crop production. 

The results of this study demonstrated that consistent production of 
early maturing grain sorghum was possible under southern Alberta 
conditions and that yields corresponded closely to those of spring wheat. 
The yield of sorghum in rotation was similar to that of wheat; sorghum 
yields on stubble were 63% of those on fallow compared with 69% for 
wheat. From an economic standpoint, a 3-year rotation including sorghum 
in the first year, spring wheat or winter wheat in the second year, and 
fallow in the third year is likely to be most desirable. Because of the 
low price of sorghum relative to that of wheat, however, economic returns 
from rotations including sorghum would likely be considerably lower than 
from conventional spring wheat or winter wheat rotations. As well, its 
inconsistent stand establishment in spring predisposes sorghum to weed 
and disease infestations so that agronomic management requirements for 
sorghum are more intensive than those of traditional cereals. 
Consequently, the inclusion of sorghum in crop rotations in southern 
Alberta cannot currently be recommended until the problems of stand 
establishment and low yield have been overcome. 



- 22 



4000 -i 



3000- 



C0 

O) 
XL 



2000- 



1000- 



sorghum (fallow) 

sorghum (stubble) 

wheat (fallow) 

wheat (stubble) 




100 200 300 400 

Available water (mm) 



Fig. 5. Relationship between yield and total available water (soil 
moisture + growing season precipitation) for sorghum and spring wheat 
grown on fallow and stubble from 19781984. (R 2 for the relationships 
in the order in which they appear in the legend: 0.78, 0.64, 0.97, 0.84) 



- 23 



Harvest 

The forage sorghums have the coarsest stems and the sudangrasses have the 
finest stems. Thus the sudangrasses are the easiest to harvest for hay 
as they will dry in the swath more rapidly. They are also more suitable 
for grazing. There is seldom sufficient moisture available for regrowth 
in southern Alberta so the harvest date should be dependent on the time 
when growth ceases so that yield is maximized. Sorghum-sudangrass hybrids 
grown on irrigation will have a high moisture content and it may not be 
possible to dry the swath. Irrigated sorghum should probably be preserved 
as silage. 

Grain sorghum should be direct -combined with the cutter bar raised so 
that only the heads enter the combine. If a frost has not killed the 
stems they will remain green even when the grain is mature so it is 
important to minimize the amount of tissue entering the combine. The 
ideal moisture content for combining grain sorghum in southern Alberta is 
between 18 and 25%. If the crop is allowed to dry to 14% or less, some 
stalk breakage may occur and yield will be reduced. If the crop is 
harvested at moistures greater than 14%, aeration or drying will be 
necessary. The cylinder speed has to be carefully adjusted so that the 
hulls are removed from the seed. 



- 24 - 



LITERATURE CITED 

1. Gardiner, E. E., Dubetz, S. and Major, D. J. 1981. Sorghum, wheat 
and corn in diets for broiler chicks. Can. J. Anim. Sci. 61: 
511-513. 

2. Gardiner, E. E., Major, D. J. and Dubetz, S. 1982. Substitution of 
sorghum for wheat in diets for laying hens. Can. J. Anim. Sci. 62: 
305-306. 

3. Garrity, D. P., Watts, D. G. c, Sullivan, Y. and Gilley, J. R. 
1982. Moisture deficits and grain sorghum performance: 
evapotranspirat ion-yield relationships. Agron. J. 74: 815-820. 

4. Gaudet, D. A. and Kokko, E. G. 1986. Seedling disease of sorghum 
grown in southern Alberta caused by seed-borne Pseudomonas syringae 
pv. syringae . Can. J. Plant Path. 8: (in press). 

5. Gaudet, D. A., and Major, D. J. 1986. Factors affecting seedling 
emergence of sorghum for short-season areas. Plant Dis. 70: 572-575. 

6. Hegde, B. R., Major, D. J., Wilson, D. B. and Krogman, K. K. 1976. 
Effects of row spacing and population density on grain sorghum 
production in southern Alberta. Can. J. Plant Sci. 56: 31-37. 

7. Hobbs, E. H. and Krogman, K. K. 1981. Sorghum and barley in 
southern Alberta: Grain yield response to irrigation and 
fertilizer. Can. J. Plant Sci. 61: 837-842. 

8. Hunt, B. J. and Taylor, A. O. 1976. Hydrogen cyanide production of 
field- grown sorghums. N. Z. J. of Exper. Agric. 4: 191-194. 

9. Janzen, H. H., Major, D. J. and Lindwall, C. W. 1987. Comparison 
of crop rotations for sorghum production in southern Alberta. Can. 
J. Plant Sci. (in press). 

10. Major, D. J. 1980. Photoperiod response characteristics 
controlling flowering of nine crop species. Can. J. Plant Sci. 60: 
777-784. 

11. Major, D. J. and Haraman, W. M. 1981. Comparison of sorghum with 
wheat and barley grown on dryland. Can. J. Plant Sci. 61: 37-43. 

12. Major, D. J., Hamman, W. M. and Rood, S. B. 1982. Effects of 
short -duration chilling temperature exposure on growth and 
development of sorghum. Field Crops Res. 5: 129- 136. 

13. Major, D. J. and Wilson, D. B. 1982. Sorghum production in dryland 
short-season conditions. Proc. 37 Annu. Corn and Sorghum Ind. Res. 
Conf. 37: 10-25. 



- 25 - 



14. Neild, R. E. 1982. Temperature and rainfall influences on the 
phenology and yield of grain sorghum and maize: a comparison. 
Agric. Meteorol. 27: 79-88. 

15. Olson, T. C. 1971. Yield and water use by different populations of 
dryland corn, grain sorghum, and forage sorghum in the western corn 
belt. Agron. J. 63: 104-106. 

16. Peacock, J. M. and Heinrich, G. M. 1984. Light and temperature 
responses of sorghum. Pp. 143-158 in Agrometeorol. of Sorghum and 
Millet in the semi-arid tropics. S. M. Virmani and M. V. K. 
Sivakuraar, eds. Proc. Int. Symp. 15-20 Nov 1982, ICRISAT Center, 
India. Patancheru, India. 

17. Porter, K. B., Jensen, M. E. and Sletten, W. H. 1960. The effect 
of row spacing, fertilizer and planting rate on the yield and water 
use of irrigated grain sorghum. Agron. J. 52: 431-434. 

18. Ross, W. M. and Webster, O. J. 1970. Culture and use of grain 
sorghum. USDA/ARS Agric. Handbook No. 385. 

19. Stewart, B. A., Musick, J. T. and Dusek, D. A. 1983. Yield and 
water use efficiency of grain sorghum in a limited 
irrigation-dryland farming system. Agron. J. 75: 629-634. 



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